Block copolymers comprising at least one block of a polymerized monoalkenyl aromatic compound, e.g., styrene, and at least one block of a polymerized conjugated alkadiene, e.g., butadiene, are well known in the art. Certain of these materials demonstrate elastomeric properties at ambient temperature but are processed by methods conventional for thermoplastic polymers at somewhat elevated temperatures. These elastomeric block copolymers are illustrated by products known as KRATON.RTM. Thermoplastic Rubber and marketed by Shell Chemical Company. While these block copolymers find extensive utilization in a wide variety of applications, it has been found that the properties of these block copolymers are improved for other applications by hydrogenation of some or all of the carbon-carbon unsaturation in the polyalkadiene or aliphatic portion of the polymeric molecule and, on some occasions, in the poly(vinyl aromatic compound) or aromatic portion of the molecule. The selective hydrogenation of the aliphatic portion serves to provide greater resistance to oxidation and enables the polymers to be used more extensively at more elevated temperatures.
It is also advantageous on some occasions to incorporate within the polymeric molecule additional chemical moieties which permit the block copolymers to be functionalized. The functionalization of the block polymers enables a number of additional chemical processes to take place including crosslinking but also interaction with other polymeric materials. However, the potential of the non-functionalized polymer to crosslink is often a limitation on the temperature at which the polymer can be functionalized, since heating the polymer to an elevated temperature will often result in premature and undesirable crosslinking. It would be of advantage to provide a novel class of benzocyclobutene-containing selectively hydrogenated block copolymers which are further functionalized at elevated temperatures without undesirable premature crosslinking taking place.